Circuit breaker with mometary by-pass



May 2, 1967 5 Sheets-Sheet 1 G. s. HARPER ETAL 3,317,865 CIRCUIT BREAKER WITH MOMENTARY BY-PASS Filed Aug. 10, 1965 y 2, 1957 G. s. HARPER ETAL 3,317,865

CIRCUIT BREAKER WITH MOMENTARY BY-PASS Filed Aug. 10, 1965 5 Sheets-Sh et 2 y 2, 1967 G. s. HARPER ETAL 3,317,865

CIRCUIT BREAKER WITH MOMENTARY BY-PASS 3 $heets $heefr, 3

Filed Aug. 10, 1965 United States Patent CIRCUIT BREAKER WITH MOMETARY BY-PASS eralsburg, Md, assignors to Airpax Electronics Incorporated, Cambridge, Md., a corporation of Maryland.

Filed Aug. 10, 1965, Ser. No. 478,559 3 Claims. (Cl. 335-12) This invention relates to circuit breakers such as disclosed in United States patent application Ser. No. 377,- 993, filed June 25, 1964, now Patent No. 3,251,232, issued May 17, 1966. I

It has been found, in using the circuit breaker disclosed in the aforementioned application for starting electric motors, that the surge of starting current causes the breaker to open the circuit before the motor can start. It is therefore an object of this invention to provide a circuit breaker which will not open the circuit to the motor upon the initial surge of current but which will remain closed till the motor is started.

In accordance with this invention the coil or portion of the coil for operating the tripping mechanism of the circuit breaker is temporarily cut out of the circuit there by allowing the motor to get up to speed.

The invention may best 'be understood by referencee to the following description when read in conjunction with the accompanying drawings wherein:

FIGURE 1 illustrates the device in the position where the contacts are open.

FIGURE 2 illustrates the device in the position where the main contacts are closed and the auxiliary contacts are open.

FIGURE 3 illustrates the device in an intermediate position where all the contacts are closed.

FIGURE 4 is a view taken on the line 44 of FIG- URE 3 with certain parts omitted.

In the drawings is shown a metal housing 2 having secured thereto a threaded bushing 4 in which is pivotally mounted a toggle handle or lever 6 on a pivot 8. A housing 10 of insulating mate-rial is fitted in the metal housing 2 and is closed by a cover 12 of insulating material and maintained in assembled relation by a metal cover member 14 secured to housing 2.

Terminals 16, 18 are mounted by insulation 16', 18 in member 14. Terminal 16 has integral therewith a terminal 20 and terminal 18 has secured thereto a fixed contact 22 for cooperation with a movable contact 24 carried by a lever 26 pivotally and slidably mounted on a frame 28 by means of a pin 30 secured to the frame 28 and extending through a slot 32 in the lever 26. A spring 34 is wound about pin 30 and is provided with a biasing arm 36 bearing against lever 26 and reaction arms 38 bearing against the frame 28.

A lever 40 of insulating material is pivotally mounted on the frame 28 by a pivot rod 42 secured to the frame and is provided with a socket portion 44 for reception of the end of lever 6. Movement of the lever 6 about pivot 8 rotates the lever 40 about pivot 42.

A U-shaped lever 46 is pivotally connected to the lever 40 by a pivot 48 and a lever 50 is pivotally connected to lever 26 by .a pivot connection 52. The lever 50 is formed with parallel sides connected by a bridge piece 51 integral therewith and straddles lever 26 to form a structure which is symmetrical to avoid any tendency for the levers to bind or to bend the connecting pivot. The lever 46 is also formed with parallel sideswhich are conneced by bridge pieces 47 to form an integral symmetrical structure which straddles lever 50. Levers 46 land 50 are pivotally connected by a pivot connection 54. An L-shaped forked lever 56 is pivotally connected to the end of one of the legs of the U-shaped lever 46 by a pivot connection 58 Lit and is shaped to allow the entrance and exit of a pin 60, secured to lever 50, into and out of the fork groove 61.

A shaft 62 is rotatably mounted on the U-shaped lever 46 and is provided with .a cut-out section 64 which will allow the passage of the lever '56 when rotated to one position but which will prevent rotation of the lever 56 when positioned as shown in FIGURE. 1. The shaft iS also provided with an abutment in the form of a pin 66 fixed thereto.

A bell crank lever 68 is pivoted on a rod 70 fixed to the frame and has one arm 72 .adjacent an electromagnet 74 and another arm 76 which can contact and rotate the pin 66 when electromagnet 74 is energized to attract arm 72.

The pin 66 is urged by a spring 78 into contact with an abutment 80 carried by lever 46. A second abutment 82 carried by the lever 46 serves as a reaction element for the spring 78.

The circuit breaker is shown in FIGURE 2 with the contacts 22, 24 biased together by spring 34. As a conse: quence the reaction force of spring 34 on pivot 52 loads the levers 46 and 50 to tend to collapse them. However collapse is prevented by the fit of pin 60 in the fork groove 61. The force of pin 60 against lever 56 tends to pivot the lever 56 about pivot 58 and into cont-act with shaft 62. Since the lever 56 is prevented by the shaft 62 from rotating to release the pin 60, the levers 46 and 50 are maintained locked in the position shown in FIGURE 2. Only shocks and/ or vibrations of such violence, magnitude, and character that can rotate shaft 62 against the bias of spring 78 can cause unwanted collapse of the toggle mechanism.

Upon the occurrence of an overload the electromagnet '74 is energized to attract arm 72 and to cause pivoting of the bellcrank lever 68 about pivot 70. A pad 84 carried by the arm 76 is carried into contact with abutment pin 66 to thereby rotate shaft 62. Rotation of the shaft from the locking position shown in FIGURE 2 to the unlocking position presents the cut-out section 64 to the end of the lever 56 to allow the lever to rotate to release pin 66 and allow the collapse of the linkage 46, 50 to the position shown. The collapse of the linkage allows movement of lever 26 relative to pin 30 and thus separate the contacts 22, 24. The are chute 86 serves to extinguish the arc drawn by the separating contacts.

Springs 88 are wrapped about pivot 42 and have biasing arms 96 urging pivot 48 about the pivot 42 and have a reaction arm 92 hearing against the frame 28 shown as a Immediately upon the collapse segment in FIGURE 1.

of the linkage the arm moves pivot 48 and its connected lever 46 carrying lever 56 to the position shown in FIGURE 1 whereby pin 60 is again received in fork groove 61 and lever 56 held captive by shaft 62 to reform the toggle. The parts come to rest in the position shown in FIGURE 1.

To reset the device lever 6 is rotated counterclockwise about pivot 8. This rotates lever 40 clockwise about pivot 42 to carry pivot 48 about this pivot until it comes to rest against a stop not shown. The levers 46, 50 locked against pivoting relative to each other are moved as a rigid body to force lever 26 to rotate about pin 30 to close contacts 22, 24. Continued movement causes pivoting, with some sliding, about the closed contacts to return lever 26 to the position shown in FIGURE 2. The sliding of the contacts over each other gives the contacts a self-cleaning action.

An auxiliary contact plate 100 is mounted on the frame by an insulator support 102 fitted in notches 103 of the frame and is connected to terminal 20 and to a lead 104 of the electromagnet 74. A switch plate 106 is provided with a pair of protuberances 108 which are received in open- 3 ings 110 in the frame to form a pivotal mounting for the plate. The plate is also provided with an integral tab 112 which is urged into bearing engagement with lever 26 by a spring 114. A conductor 116 is connected at one end to lever 26 and at the other end to the second lead 118 of the electromagnet. A conductor 119 may be optionally provided to connect the plate and lever but is not necessary since a circuit between these points is completed by the metal parts of the frame, lever, and pivots In'the OFF position the main contacts 22, 24 and the contact surfaces of plates 100 and 166 are separated as shown in FIGURE 1. Rotation of the handle 6 to the ON position operates the toggle mechanism to pivot lever 26 about pin 30 to close contacts 22 and 24 as shown in FIGURE 2. In a position intermediate the OFF and ON positions contacts 22 and 24 are closed and the plate contacts are also closed as shown in FIGURE 3. The closing of the plate contacts completes a by-pass circuit from terminal 16, 20 through plate contacts 100, 106, lever 26, contact 24, contact 22, to terminal 18. The initial surge of current drawn by the motor for starting travels through this circuit which remains completed only momentarily, i.e., during a portion of the travel of lever 26 under the influence of thetoggle mechanism from the position where contacts 22, 24 are open to the position where the contacts are closed.

The initial closing movement of lever 26 produces pivoting of the lever in a clockwise direction about pin 30. Plate 106 is biased by spring 114 to pivot in a clockwise direction about pivotal mounting 108, 110 and tab 112 is held against the lever such that the lever and plate pivot together. Pivoting of the lever and plate continues in a clockwise direction until contacts 22, 24 close. Contacts 100, 106 close at substantially the same time and all the contacts therefore cooperate to complete the by-pass circuit. Continued movement of lever 26 under the influence of the toggle mechanism produces pivoting of the lever in a counterclockwise direction about contacts 22, 24 as a pivot. The lever therefore presses on tab 112 of switch plate 106 to pivot the plate counterclockwise about pivot mounting 108, 110 to separate the contacts 100, 106 and open the by-pass circuit as shown in FIGURE 2.

What is claimed is:

1. A circuit breaker comprising a frame, means mounting a fixed contact on the frame, a lever pivotally mounted on the frame and carrying-a contact, toggle means for pivoting the lever to close and open the contacts, manual means for operating the toggle means, an electromagnet in series with the contacts, means operated by the electromagnet to trip the toggle means on a predetermined current flow through the contacts to open the contacts, and a switch plate pivotally mounted on the frame and pivoted by the lever to short circuit the contacts immediately on closing of the contacts, and pivoted to remove the short circuit immediately thereafter.

2. A circuit breaker comprising a frame, means mounting a fixed contact on the frame, a lever'pivotally mounted on the frame and carrying a contact for cooperating with the fixed contact to complete a circuit, means for pivoting the lever from an initial position in which the contacts are open to a finally closed position in which the contacts are engaged to complete the circuit; an electromagnet in series with the contacts, means operated by the electromagnet to pivot the lever to open the contacts on a predetermined current flow therethrough, and means operated by the lever while in an intermediate position to momentarily short circuit the electromagnet while being moved from the initially open to the finally closed position.

3. An apparatus as defined in claim 2 wherein the means for temporarily short circuiting the electromagnet comprises a lever pivotally mounted on the frame, conductor means connecting the lever to the movable contact, an auxiliary contact carried by the frame for engagement by the lever, and means connecting the auxiliary contact to the electromagnet.

References Cited by the Examiner UNITED STATES PATENTS 10/1946 Van Hoorn 200-116 3/1963 Holdt 20087 

1. A CIRCUIT BREAKER COMPRISING A FRAME, MEANS MOUNTING A FIXED CONTACT ON THE FRAME, A LEVER PIVOTALLY MOUNTED ON THE FRAME AND CARRYING A CONTACT, TOGGLE MEANS FOR PIVOTING THE LEVER TO CLOSE AND OPEN THE CONTACTS, MANUAL MEANS FOR OPERATING THE TOGGLE MEANS, AN ELECTROMAGNET IN SERIES WITH THE CONTACTS, MEANS OPERATED BY THE ELECTROMAGNET TO TRIP THE TOGGLE MEANS ON A PREDETERMINED CURRENT FLOW THROUGH THE CONTACTS TO OPEN THE CONTACTS, AND A SWITCH PLATE PIVOTALLY MOUNTED ON THE FRAME AND PIVOTED BY THE LEVER TO SHORT CIRCUIT THE CONTACTS IMMEDIATELY ON CLOSING OF THE CONTACTS, AND PIVOTED TO REMOVE THE SHORT CIRCUIT IMMEDIATELY THEREAFTER. 